Apparatus for melting plastic compositions



April 6, 1948.

w. F. MIDDLESTADT APPARATUS FOR MEL'I'ING PLASTIC COMPOSITIONS FiledDec. 27, 1945 3 Sheets-Sheet l @NQA I HM Ill IIIIIIIII- WILL/AH f.I7100L6TADT Ap 6, 1948. w. F. MIDDLESTADT APPARATUS FOR MELTING PLASTICCOMPOSITIONS 3 Sheets-Shut 2 Filed Dec. 27, 1945 WILLIAM F. MDDLESTADTmvsmm April 6, 1943' I w. F. MIDDLESTADT 2,439,367

APPARATUS FOR MELTING PLASTIC COMPOSITIONS Filed Dec. 27, 1945 sSheets-Sheet s A WILLIAM E Nmmssmor INVENTOR Patented Apr. 6, 194a,

APPARATUS FOR MELTING PLASTIC COMPOSITIONS William F. Middlestadt,Baltimore, Md, assirnor to The James. Gibbons Company, Relay, Md.

Application December 27, 1945, Serial No. 837,433

This invention relates to a method of and apparatus for melting plasticmasses, particularly those used for structural purposes, for example asfillers for sealing joints of concreteconstructions, roof coatings andsealers, and the like.

It is the object of the present invention to provide arrangements forliquefying plastic masses of the hot-poured type in a manner to bringthese masses into a fluid state capable of being poured into thecrevices or joints between concrete sections without overheating themass in order not to destroy the effectiveness of the composition, inits functioning following the ,installation thereof.

It is the object of the present invention to treat sealing compositionsfor pavements, which are normally shipped in the form of solid blocks orslabs, ina manner to liquefy the same to adapt the composition to bepoured in a moltenstate by means of conventional pouring spouts or byautomatic filling machines of the type disclosed in my applicationSerial No. 600,538, filed June 20, 1945, without causing any deleteriouschemical changes to take place in the composition as a result of theheating treatment. The invention is applicable to all types of plasticcompositions used for such purposes, particularly bituminous typefillers which may be composed of various ingredients known in the art.These fillers may be formed of bituminous material alone, or bituminousmaterial with flllers, or bituminous material with rubher and fillers,as well as bituminous material with natural or synthetic resins, with orwithout fillers. The invention is of' particular utility in thetreatment of rubberized bituminous materials of the type disclosed inthe patent to Ross, No. 1,817,933, or in the commercial products such as"Sealz marketed by Dispersions Process, Inc., a subsidiary of UnitedStates Rubber Co, or Para Plastic, manufactured and distributed byServicised Products Company, Chicago, Illinois.

According to past practices, the heating of the compositions of thetypes described above in standard asphalt kettles, to bring the productsinto a molten state for the purposes of enabling the pouring anddepositing of the same into the joints between concrete, sections, hasresulted in the burning, oxidation and charring of the mass, causing achemical breakdown or segregation of the constituents of the compositionso that fol- 3 Claims. (Cl. 126-3435) lowing the heating operation thesealing properties of the material would thereafter be destroyed. Thiswas true despite the care with which the materials were prepared and therelatively high cost of the ingredients which were intended to renderthe sealing composition adaptable to perform the scaling functions underfreezing weather conditions and repeated expansive and contractilemovements of the pavement sections between which the composition wasadapted tobe poured and adherently aiilxed to the lateral .wallsthereof.

The invention proceeds upon the principle of bringing the solid lumps ofthe sealing material into a molten state adapted for pouring withoutpossibility of overheating of the mass, or the heating thereof in'anunduly rapid manner which causes the carbonization of the bitumen, themelting of the rubber. or any other undesired deleterious eflfects uponthese and other ingredients of the sealing compositions. By means of theinvention, the composition is rendered fluid at a temperature below thenormal melting point of the composition, and far below any point atwhich any of the ingredients undergoes any chemical change or thatatwhich any chemical breakdown or segregation of the constituents takesplace. a v r l'his general objective is attained by applying acontrolled degree of heat to the mass of material from its solid stateto its ultimate molten state while mechanically manipulating theparticles of the mass to supplement the heating thereof so that no partsthereof may reach tem peratures sufficiently high to exert a destructiveefl'ect upon the chemical properties of the composition or the severalingredients thereof. The heating is performed by indirect means so thatthe composition at no time is exposed to any hot spots, and the controlmay be rendered automatic so that the heating range may be kept withinpredetermined limits without the necessity of human intervention,assuring that the requirements of the specifications in the handling ofthe different materials may be attained. In addition to the heat, whichis applied extern-ally by means of heated air or liquid, or insulatedelectrical heat, internal heat is produced in the mass by the attritionof the particles thereof as'the same are Passed through rotary pumpssuch as ther serve to bring the individual particles into more intimateheat exchange relationship with the surrounding source of indirect heat.Thus, the combination of indirect heat with the manipulation ormastication of the plastic mass as may be attained by the recirculationof the molten mass through a gear pump, result in a rapid and effectivemode of rendering the mass fluid without any tendencies for theconstituents thereof to separate or segregate, whereupon the mass is incondition to pour by wtihdrawing the .same from the apparatus intoportable kettles or any other pouring devices of the prior art of thetype shown in the above mentioned application, Serial No. 6001538. Ifdesired, the apparatus in accordance with the present invention may formpart of the pouring unit as shown in said application.

Other objects and purposes will appear from the detailed description ofthe invention following hereinafter, taken in conjunction with theaccompanying drawings, wherein Fig. l is a vertical sectional view withcertain .parts in elevation of a preferred embodiment of the invention;

Fig. 2 is a vertical sectional view along line 2-2 thereof; and

Fig. 3 is a vertical sectional view of another simplified embodiment ofthe invention.

In Figs. 1 and 2 is shown one embodiment of the apparatus for meltingsolid blocks of plastic material P, which may be of the bituminous typ senumerated above. This apparatus may be a stationary installation or maybe mounted upon a truck or other vehicle to render the same portable.The blocks 1?, in the form of small pieces of about pounds, may be cutfrom larger blocks. and are fed into a hopper I opening into a casing 2'in which a piston 3 is adapted to operate to press or extrude a mass ofthe plastic material in advance of the piston through a series of pipes4 which are shown-of U-shaped configuration in Fig. 1. The piston isformed with an integral valve element 3' to prevent the entry of theblocks P behind it in'order not to interfere with the working stroke ofthe piston which is actuated from a hydraulic cylinder 20 having inletconduit 2i and outlet conduit 22 operative at the opposite ends of thecylinder to alternately control the working piston 23 interconnectedwith piston 3 and of smaller cross sectional area than the latter in thecasing 2 in order tomultiply the force exerted upon the plastic massbeing extruded through the pipes 4. The hydraulic unit is activated bythe pump 24, which may be driven by Sprocket 25, gears or any othersuitable transmission from a drive shaft 26 which is' coupled at the end26' thereof to an internal combustion engine, electric motor or anyother form of prime mover. The liquid of the hydraulic unit iscontrolled by the valve casing '21 which controls the communicationbetween the outlet of the pump and the conduits 2i and alternativelywith the outlet of the pump and the by-passing of the circulating fluidthrough the tank 28. A hydraulic actuating unit of the type disclosedmay assume various forms and is indicated only generally, since theessential features of the invention are not concerned therewith.

As shown in Fig. 2, the casing 2 and the piston 3 are of rectangularconfiguration and the number of tubes or conduits 4 opening into thischam-- ber may be varied depending upon the desired capacity of theapparatus. Thus, there may be as 4 many as 50 one-half inch, outsidediameter. tubes fed from a single plunger or piston. These tubes may beof configurations other than U-shaped as shown in the drawing, forexample, spiral or serpentine. The tubes 4 are disposed at the upperpart of the housing l0 which may be enclosed by an insulating Jacket IIand provided with a vent l2. The housing III is filled with a heatedfluid medium F which may be oil. This fluid medium may be heated bymeans of a fuel oil burner is disposed at the end of tube H whichdirects the combustion gases along the base of the housing and reversesdirection in portion Ila and exhausts to the atmosphere through theupwardly extending portion Ilb which may be disposed as a stack .in heatexchange relation to one end of the housing l0 and in the path of whichmay be disposed the casing 2 containing the plastic mass to cause asoftening up of the material prior to the extrusion thereof through thepipes 4. The extruding pressures upon the plastic material into theplurality. of pipes communicating with the casing 2 give rise to anattrition of the particles of the mass to cause a frictional heat to begenerated therein, which, in conjunction with the heat of the fluidmedium F surrounding the pipes, serve to melt the plastic mass withoutany local hot spots and with no possibility of chemical change of theingredients of the plastic mass. While the discharge of theplastic massfromthe ends ii of the pipes 4 might be accumulated in a dispensing unitfor pouring purposes. a reater degree of fluidity may be imparted to themass by permitting the same to drop into the chamber l6 disposed at thebase of the housing which is also surrounded by the fluid mass F andwhich is maintained in a desirably heated state by the proximity theretoof the combustion gas flues l4 and Ma. The chamber i8 discharges throughthe outlet conduit I! to a gear pump it which recirculates the moltenmass through the outlet of the gear pump and the conduit is to the topof the chamber 16. Not only does the gear pump serve to render uniformthe degree of heat in the mass of molten material undergoingrecirculation, but the same in addition serves to masticate theparticles of the mass to supplement the mastication imposed originallyon the particles in the extruding operation through the tubes 4. Acontrol valve 30 in the conduit is may be operated selectively to permitcirculation to take place or to block the same in conduit l9. This valvemay be operated conjointly with another control valve 3! in outletconduit 32 in order to permit selective withdrawal of the fluid materialfrom the outlet of the gear pump in conjunction with of the body of oilF in the housing ill, a pipe 35,

extending upwardly through the housing, may be connected to a secondaryor auxiliary circulating pump 38, having the outlet thereofcommunicating with the base of the housing in order to set up a forcedcirculation of the heating fluid. Any

body of liquid, or even air, may be used as the heating mediumF in thehousing. Pump 36 may "be driven by any suitable source of motive power,

and as shown in Fig. 1, the same may be driven from pump l8 by the chain36c.

As shown in the drawings. the drive shaft 28 operating the hydraulicpump 24 may be also I used to drive the recirculating gear pump l8, as

shown in Fig. 2. These drives may be taken off shall comply with thedetail requirements spe cified below. The material shall not be damaged.

when heated to the temperature required for satisfactory pouring.

lated, or as shown in Fig. 3, they may take the form of insulatingheating tubes 42 in which the heating elements are covered by 'a ceramiccoating so'that the plastic mass may flow in contact therewith and maybe melted down to a plastic mass which gravitates to the bottom of thehousing 50, as shown in Fig. 3. a

A thermostatic control element 52" may be mounted upon bracket 5| andmayembody an indicating thermometer or pyrometer which is connected toone of the heating elements and the electric circuit for the heatingelements may be controlled automatically by a thermostat in order tolimit the heating of the elements so that no charring or undesired localburning of the plastic mass will take place. A supplemental temperatureindicating instrument 53 may be disposed in the lower portion of thehousing to indicate the temperature of the liquid mass of plasticmaterial which is discharged from the conduit 53 and which may berecirculated by the recirculating pump 54 to the conduit 55 whichdischarges into the top of the housing at 56. By selectively operatingthe valve 51 in outlet conduit 58, some" of the material issuing fromthecirculating pump 54 may be withdrawn for utilization, while some isrecirculated to effect amastication of the plastic mass particles whilesubjecting them to heat- Material furnished under this. specificationwhen tested in accordance with the methods described in section F shallconform to the following requirements:

(a) Pour point, not more than 450 F. (b) Melting time, not more than 60min. (0) Penetration:

At 32 1 2,200 g., 60 a... not less than 0.28 cm.

At 77 F., 150 g.', 5 sec., 0.45 to 0.75 cm. (Id) Flash point, not lessthan 550 F. (e) Flow, notmore than 05 cm. (i) Bond test.

There shall be no cracking of the material or failure in bond betweenthe materials and the mortar test blocks at the end of five cycles.

By means of the invention, the material is not damaged when heated forpouring purposes as required in the third paragraph above, which occurs1when the usual types of asphalt kettles are use Aside from the specificmaterials mentioned above, all types of plastic compositions subject todamage upon'overheating may be melted in accordance with the presentinvention.

While I have described my invention as embodied in a specific form andas operating in a specific manner for purpose of illustration, it

' should be understood that I do not limit my exchange with the heatingelements 42 disposed in the housing 50.

In the handling of certain materials, it may be desirable to increasethe masticating-elfects of the circulating pumps, whereupon a pluralityof such pumps may be disposed in series in the conduits issuing from thehousing; in the embodiment of the invention shown in Fig. 3 these may bedisposed in either the conduit 55 and/or the conduit 58 so that themastication is eifected incidental to the recirculation of the material,or

immediately prior to its discharge from the heat exchange apparatus.Thus, as shownin Fig. 3, circulating pump 54 adds to the masticatingeffect performed by the pump 54.

The invention disclosed herein has been found particularly useful andeffective in the preparation of expansion joint fillers of the hotpouredtype for joint-sealing of concrete sections, Federal specifications forwhich may be found in Federal Standard Stock Catalog, Section IV,

part .5, SS-F-336, May 6, 1942. Theseare as folinvention theretmsincevarious modifications will ,-,suggest themselves to those skilled in"the art without departing from the spirit of my invention, the scope ofwhich is set forth in the annexed claims.

I claim:

1. An apparatus for transforming a solid thermoplastic rubberycomposition composed of rubber and/or bitumen, resins and inert fillersto a liquid pourable state, comprising a closed housing containing aheated liquid medium therein, a combustion gas conduit for heating saidliquid medium, conduits disposed in said housing, hydraulically operatedmeans for forcing said thermoplastic rubbery composition through saidconduits in heat exchange relation to said liquid medium to transformsaid composition into molten particles, a container in said housing forreceiving the extruded molten particles of said composition and meansfor applying additional heat thereto to liquefy the composition for hotflow purposes with no chemical breakdown or segregation of theconstituents thereof, a pipe extending into said housing and openinginto said container, a recirculating pump having the inlet thereofconnected to the outlet of said container and the outlet of said pumpconnected to said pipe and control valve means in said pipe forcontrolling the quantity of the molten mass undergoing recirculation inand withdrawal from the apparatus.

2. An apparatus as set forth in claim 1, including a secondarycirculating pump for maintaining the heated liquid medium incirculation.

3. An apparatus as set forth in claim 1, including a secondarycirculating pump for maintaining the heated liquid medium in circulationand a prime mover for actuating the hydraulically operated forcing meansand said recirculating and secondary circulating pumps.

' WILLIAM F. MIDDLESTADT.

(References on following page) Number Number Name Date Downard July 2,1935 Crane Feb. 7, 1939 McQueer May 14, 1940 Bailey July 9, 1940 Dons,et a1. Oct. 1, 1940 Rogers Jan. 7, 1941 Gordon June 16, 1942 Hanson Feb.1, 1944 Kittle et a1. Mar. 12, 1946 FOREIGN PATENTS Country Date FranceJan. 2, 1931 France Apr. 11, 1936

